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Interannual Variability in the Extratropical Ocean Carbon System

Interannual Variability in the Extratropical Ocean Carbon System. Scott Doney ( WHOI). -Ubiquitous!! -Physical climate modes -Mechanisms & climate change -New approaches & experimental designs. Hawaii Ocean Time-Series. Dore et al. (2002). Interannual Variability in Global Carbon Cycle.

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Interannual Variability in the Extratropical Ocean Carbon System

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  1. Interannual Variability in the Extratropical Ocean Carbon System Scott Doney (WHOI) -Ubiquitous!! -Physical climate modes -Mechanisms & climate change -New approaches & experimental designs Hawaii Ocean Time-Series Dore et al. (2002)

  2. Interannual Variability in Global Carbon Cycle Atmospheric CO2 growth rate Francey -Ocean sequesters ~30% of fossil fuel CO2 -Variability dominated by land sinks but role for the oceans -Primary global signal associated with ENSO events

  3. ocean model atmosphere data Equatorial Pacific El Niño : 0.2-0.4 PgC/y Non El Niño : 0.7-0.9 PgC/y Average: 0.6±0.2 PgC/y -Dense time/space coverage -Agreement among field data, ocean models & “top-down” atmospheric estimates Bousquet et al. (2000) Le Quere et al. (2000) (also Obata et al. 2003) 1997-2002 Feely et al. (2003)

  4. Natural Climate Modes Surface Pressure Anomaly NAO: North Atlantic Oscillation PDO: Pacific Decadal Oscillation AAO: Antarctic Oscillation -Shift of mass from subpolar lows and subtropical highs -Changes in winds, SST, ocean convection, freshwater flux, … -”Intrinsic” atmospheric variability (ocean, stratosphere) -Tropical-extratropical interactions NAO Wang and Schimel (2003)

  5. Regional Spatial Patterns -Modes expressed on regional (sub-basin) scales with significant cancellation (dipole pattern) -Historical and future climate change appear to project onto natural modes -Spatial patterns may evolve with time Wang and Schimel (2003) -0.6 Correlation +0.8 models NAO Index obs. 1900 2050 1950 2000

  6. SubtropicalNorth Atlantic Mixed Layer Negative NAO=> +WML -SST +entrainment +production +CO2 uptake Extrapolate to subtropical gyre => ±0.2 PgC/y whole basin => ±0.3 PgC/y CO2 uptake Entrainment Transport Production Gruber et al. (2002)

  7. Pacific Decadal Oscillation ML Anomaly + Wang & Schimel (2003) + PDO Depth Integrated Chlorophyll Subtropical nutrient limited prod. +ML => +Chlorophyll + Production Subpolar/Polar light limited prod. -ML => +Production multiple impacts on higher trophic levels (e.g. zooplankton, fisheries, mammels) Karl et al. (2001) Hare & Mantura (2000)

  8. Climate Change Response productivity Sarmiento et al. (submitted) -Regional climate change signals -Surface warming, high latitude freshening, increased stratification, reduced mixed layer depths & sea-ice -Productivity lower in subtropics, higher in subpolar

  9. Multi-Century Coupled Carbon/Climate Simulations +1.5 14.1 -1.5 13.6 Surface Temp. Net CO2 Flux (Pg C/yr) 0 200 year Fung, Doney, Lindsay & John -Fully prognostic land/ocn BGC and carbon/radiation -“Stable” carbon cycle and climate over 200y -Projection of climate change on natural modes -Detection & attribution

  10. 10 Air-sea flux 3 1 .3 .1 Variability Mechanisms Particle export Fresh- water mol C/m^2 -Regions of high variability in North Atlantic & Pacific, tropics and Southern Ocean -Mechanisms differ across regions Fung, Doney, Lindsay & John

  11. Atmospheric Dust Deposition -Significant interannual variability, particularly in the North Atlantic -Driven mostly by atmospheric transport, not sources -Largest fraction is synoptic, within month variability (standard deviation/mean) Mahowald et al. (2003)

  12. Iron flux Zonal Anomalies Air-sea CO2 flux N2 Fixation Doney, Dusenberry, Moore & Mahowald

  13. SeaWiFS Ocean Color Data (1997-2003)

  14. Coherent Regional-Scale Patterns SeaWiFS Monthly Anomaly SeaWiFS Monthly Anomaly April 2000 Oct. 1998

  15. Antarctic Circumpolar Wave Le Quere et al. (2002) -Positive/negative physical anomalies propagate around southern ocean with 8-10 year time-scale -Ocean color variability appears coherent across basin -Differential regional biological responses to mixed layer depth changes depending on light versus nutrient limitation

  16. New Technology & Observational Paradigms time Centuries Repeat Sections Decadal Ship Time-Series Atm. CO2O2/N2 Inter-annual Moored Time-Series Surface transects Floats/drifters Ocean Observatories Seasonal Remote sensing Process Studies Daily space Hourly Ocean Basin Local Regional (500 km) Globe

  17. Conclusions -Common feature of almost all ocean time-series -Regional time-space structured by climate modes & biology -Natural experiments for studying climate change response -Require more spatially “extensive” design for ocean observation Acknowledgements J. Dusenberry & S. McCue WHOI K. Lindsay NCAR NSF and NSF/ONR NOPP CCSM & the NCAR CSL

  18. Global & Extratropical Variability LeQuere: ±0.4 (70% Eq. Pac.) Obata: ±0.23 (>50% Eq. Pac. ~30% Southern) -Only partial reconciliation with atmosphere inversions -Poor data coverage outside of equatorial Pacific LeQuere et al. (2000) Obata et al. (2003) Bousquet et al. (2003)

  19. Regional Spatial Patterns Wang and Schimel (2003) -0.6 Correlation +0.8 -0.6 Correlation +0.8 -Modes expressed on regional (sub-basin) scales with significant cancellation (dipole pattern) -Historical and future climate change appear to project onto natural modes -Spatial patterns may evolve with time

  20. Monthly SeaWiFS Ocean Color Anomalies standard deviation standard deviation/mean

  21. ocean model data atmosphere Le Quere et al. (2000) Bousquet et al. (2000) Equatorial Pacific physics -DIC supply (dominant) & export out of phase -General agreement among field data, ocean models & “top-down” atmospheric estimates -But what about the extratropics? air-sea flux export Obata et al. (2003) Obata et al. (2003)

  22. Antarctic Circumpolar Wave -Ocean response to annular mode in the atmosphere -Different regional biological responses to mixed layer depth changes -Air-sea CO2 flux correlated with wind stress/speed Le Quere et al. (2002) Wind Stress & CO2 flux Anomalies +0.1 Obata et al. (2003) -0.1

  23. Global Carbon Cycle -Ocean sequester ~30% of fossil fuel CO2 -Human perturbations overlay large natural background C cycle -Climate responses and feedbacks of ocean C sink not well known Doney and Schimel (2001)

  24. Winds, Heat & Freshwater Fluxes Dust/iron CO2 O2 Light Net Community Prod. Circulation Regenerated Prod. Winter mixed layer Nutrient/ DIC Supply Export Remineralization Physical & Biological Controls pCO2 = f(Temp., Salinity, DIC, Alkalinity) + (+) +-

  25. Community Structure & Higher Tropic Levels -Impacts on both biomass and species competition -Multi-decadal “regime shifts” integrating higher frequency climate variability Greene et al. 2003 Chavez et al. 2003

  26. Climate Modes & Change Change

  27. SeaWiFS Ocean Color Data (1997-2003)

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